thanks dawncr. She is right. As well as I bake, I just threw seven cakes in the trash trying to come up with a vanilla vegan cake. But you know what? I nailed it on the eighth try and it was a huge hit, even with the non-vegans. I now offer it in my business. That scary task (it was a wedding cake) led to a business opportunity I never planned to persue.
There are a bunch of us here to help if you really want to persue this. I agree that the first thing you need to look at is are you over-baking. When I practice a new cupcake recipe, I put in one or two to test. This is not popular, but I actually pull them out when the crumbs are still a little damp. The top should be moist, but still bounce back if touched.
By the way, most of my cupcakes are heavy and moist. Many trials and errors went into these recipes. And ask any scratch baker... we are always looking for that recipe that will top our very best. It is an obsession, but a fun one.
Hopefully someone will give you a good recipe for yellow cake. Mine is rather odd and requires a few odd and pricey ingredients. I have had no luck with Sylvia Weinstock's as a cupcake. It shrinks and makes a smaller cupcake. The cake is good, but I don't like the looks of the cc.
It sounds like you have a good recipe, just work on it. When you master that one, try to "one up" yourself with each flavor. If you ask a scratch question on CC, you will get answers.
I highly recommend Shirley Corriher's book, Bakewise, as a fantastic reference book. I also google all of my problem issues. I also copy and file great ideas and baking dilemmas from here for future reference. For example, I have never had a ganache problem. But I keep a file of odd situations I have read here so that if I ever get in a jam, I go to my ganache file. But you know what... reading all of the great advice here and putting it into practice is what I credit for my ganache success.
Good luck and ask away.